The disclosure relates to articles fabricated from polycarbonates and methods of making these articles using the polycarbonates.
Polycarbonates are widely used in a variety of applications by virtue of their excellent physical properties, such as impact resistance, mechanical characteristics, transparency, and the like. Polycarbonates have been used extensively for optical media applications such as for data storage and retrieval. Bisphenol A (BPA) polycarbonate, by virtue of its low cost, good transparency, and mechanical properties has served as the substrate of choice for optical data storage media such as compact disks and digital versatile disks (DVD). However, the need to store greater amounts of information on individual disks has resulted in newer techniques for high-density data storage, based on multiple information layers and shorter wavelength lasers, such as. high density DVD (HDDVD), digital video recordable (DVR), DVD-recordable (DVDxe2x88x92R or DVD+R), and DVD-rewritable (DVDxe2x88x92RW or DVD+RW) formats. The transparent plastic layer that forms the non-interfering shielding on such optical media disks requires more demanding material specifications, such as high transparency, heat resistance, low water absorption, ductility, and fewer particulates that standard BPA homopolycarbonate cannot meet.
One of the properties that influences the efficacy of a given material for higher data storage density is the spacing between the pits and grooves on the substrate material. Since data is stored in these pits and grooves, the flatness of the disk is necessary to prevent loss of information. It is known that excessive moisture absorption can result in skewing of the disk or the film, which in turn leads to reduced reliability. This skewing, hereinafter referred to as dimensional stability, will result in data being stored or read inaccurately by the laser beam. Since the bulk of the disk is comprised of a polymer material, the flatness of the disk depends on the low water absorption of the polymeric material. Similarly, a film produced from BPA polycarbonate can exhibit warpage due to absorption of ambient moisture. The dimensional stability is a function of, among other factors, the amount of ambient moisture present as well as the rate of moisture absorption. In addition to possessing optimum dimensional stability, a satisfactory material for such advanced format optical disks should also exhibit optimum replication and cycle time vis-à-vis the conditions for manufacturing conventional optical disks, such as compact disks. In order to produce disks through, for example, injection molding, the polymer should also be easily processible, that is, exhibit good flow. Therefore, there is a continued need for developing new materials as suitable substrates that would serve these advanced data storage formats. Suitable materials for high-density storage formats should satisfactorily address the requirements of dimensional stability, in addition to replication and cycle time, without compromising on any of the other desirable characteristics that BPA homopolycarbonate already possesses.
Polycarbonates having high glass transition temperatures and enhanced resistance to thermal degradation are highly sought after materials by industries, particularly those serving the automotive, aircraft, and display devices markets. In the automotive industry, they may be used, for example, in the production of headlamp lenses, such as those for headlamps and fog lamps, which are becoming smaller in size and characterized by closer proximity of the lenses to the heat-generating source. Other automotive lighting applications of such polycarbonates include articles such as bezels used for headlamps and fog lamps. Another application of such polycarbonates is for producing transparent, high temperature-stable films that can, for example be utilized in display devices.
Polycarbonates can be manufactured by direct reaction of an aromatic dihydroxy compound, such as BPA with phosgene using the so-called interfacial method, or the transesterification method, also sometimes referred to as the melt method, which involves an ester exchange reaction between the aromatic dihydroxy compound and a carbonic acid diester, such as diphenyl carbonate. The melt process gives a polycarbonate which generally contains very low levels of inorganic impurities and particulates, and which exhibits outstanding stability under polymer processing conditions.
Japanese Kokai Patent Application 7-003002 discloses manufacture of polycarbonates from cyclic terpene containing polyhydric phenols of undisclosed structures. Japanese Kokai Patent Application 8-198791 discloses polycarbonates obtained by polymerization of 1,3- and 2,8-bis(hydroxyaryl)cyclohexane derivatives. However, the average weight molecular weights of the polycarbonates were below 10,000, and the glass transition temperatures reported were also relatively low making these polycarbonates inferior candidates for fabricating articles for applications, optical media applications and display devices.
Briefly, one embodiment of the disclosure is an optical disk comprising a polycarbonate layer, wherein the polycarbonate is produced using a bis(hydroxyaryl)cyclohexane selected from the group consisting of the formula: 
wherein each A1 is independently a divalent substituted or unsubstituted radical; and at least one aromatic dihydroxy compound comonomer of the formula:
HOxe2x80x94A2xe2x80x94OH,
wherein A2 is selected from divalent substituted or unsubstituted aromatic radicals and, wherein the polycarbonate produced comprises a weight average molecular weight of at least about 10,000, a glass transition temperature of at least about 100xc2x0 C., and a percentage elongation of less than about 0.025% relative to its initial length following exposure to nitrogen with a relative humidity of about 100%, at a temperature of about 23xc2x0 C., and for a duration of about 3 hours.
Another embodiment is an article comprising a polycarbonate produced by using bisphenol composition comprising at least one bis(hydroxyaryl)cyclohexane selected from the group consisting of: 
at least one aromatic dihydroxy compound comonomer having the formula:
HOxe2x80x94A2xe2x80x94OH,
wherein A2 is selected from divalent substituted or unsubstituted aromatic radicals.
In another embodiment, an optical disk comprises a polycarbonate layer produced using a catalyst composition and a monomer composition, wherein the monomer composition comprises a diphenyl carbonate; a bisphenol composition, and an aromatic dihydroxy comonomer compound, wherein the aromatic dihydroxy compound comprises resorcinol, bisphenol A, 4,4xe2x80x2-(1-decylidene)-bisphenol, 2,2-bis (3-sec-butyl-4-hydroxyphenyl)propane, and combinations comprising at least of the foregoing aromatic dihydroxy comonomer compounds, and wherein the bisphenol composition comprises at least one bis(hydroxyaryl)cyclohexane selected from the group consisting of: 
wherein each A1 is independently a substituted or unsubstituted divalent aromatic radical.
A display device comprising a polycarbonate protective layer, wherein the polycarbonate is produced using a bis(hydroxyaryl)cyclohexane selected from the group consisting of the formula: 
wherein each A1 is independently a divalent substituted or unsubstituted radical; and at least one aromatic dihydroxy compound comonomer of the formula:
HOxe2x80x94A2xe2x80x94OH,
wherein A2 is selected from divalent substituted or unsubstituted aromatic radicals and, wherein the polycarbonate produced comprises a weight average molecular weight of at least about 10,000, a glass transition temperature of at least about 100xc2x0 C., and a percentage elongation of less than about 0.025% relative to its initial length following exposure to nitrogen with a relative humidity of about 100%, at a temperature of about 23xc2x0 C., and for a duration of about 3 hours.
The disclosure further relates to methods for making such articles from the above polycarbonates. The embodiments of the present disclosure have many advantages, including the ability to fabricate articles and films suitable for high heat, and optical data storage/retrieval applications.
In various embodiments, articles fabricated from polycarbonates are disclosed, wherein the polycarbonates are prepared using bis(hydroxyaryl)cyclohexanes and a method selected from the group consisting of melt transesterification polymerization, interfacial polymerization, interfacial conversion bischloroformate, solid state polymerization, and thin film melt polymerization.
In one embodiment, articles fabricated from the polycarbonates are produced by interfacial polymerization by using phosgene and a bisphenol composition comprising: i) at least one bisphenol selected from the group of bis(hydroxyaryl)cyclohexanes consisting of formulas (I), (II), and combinations comprising at least one of the bis(hydroxyaryl)cyclohexanes, 
wherein each A1 is independently a substituted or unsubstituted divalent aromatic radical; and optionally, at least one aromatic dihydroxy comonomer compound having the formula (III):
HOxe2x80x94A2xe2x80x94OH,xe2x80x83xe2x80x83(III)
wherein A2 is selected from divalent substituted or unsubstituted aromatic radicals.
In some embodiments, A2 has the structure of formula (IV): 
wherein G1 represents an aromatic group, such as phenylene, biphenylene, naphthylene, etc. E may be an alkylene or alkylidene group such as methylene, ethylene, ethylidene, propylene, propylidene, isopropylidene, butylene, butylidene, isobutylidene, amylene, amylidene, isoamylidene, etc., and may also consist of two or more alkylene or alkylidene groups connected by a moiety different from alkylene or alkylidene, such as an aromatic linkage; a tertiary amino linkage; an ether linkage; a carbonyl linkage; a silicon-containing linkage; or a sulfur-containing linkage such as sulfide, sulfoxide, sulfone, etc.; or a phosphorus-containing linkage such as phosphinyl, phosphonyl, etc. In addition, E may be a cycloaliphatic group.
Suitable examples of E include cyclopentylidene, cyclohexylidene, 3,3,5-trimethylcyclohexylidene, methylcyclohexylidene, 2-[2.2.1]-bicycloheptylidene, neopentylidene, cyclopentadecylidene, cyclododecylidene, adamantylidene, and the like; a sulfur-containing linkage, such as sulfide, sulfoxide or sulfone; a phosphorus-containing linkage, such as phosphinyl, phosphonyl; an ether linkage; a carbonyl group, a tertiary nitrogen group; or a silicon-containing linkage such as silane or siloxy. R1 represents hydrogen or a monovalent hydrocarbon group such as alkyl, aryl, aralkyl, alkaryl, or cycloalkyl. Y1 may be an inorganic atom such as halogen (fluorine, bromine, chlorine, iodine); an inorganic group such as nitro; an organic group such as alkenyl, allyl, or R1 above, or an oxy group such as OR; it being only necessary that Y1 be inert to and unaffected by the reactants and reaction conditions used to prepare the polycarbonate. The letter m represents any integer from and including zero through the number of positions on G1 available for substitution; p represents an integer from and including zero through the number of positions on E available for substitution; xe2x80x9ctxe2x80x9d represents an integer equal to at least one; xe2x80x9csxe2x80x9d is either zero or one; and xe2x80x9cuxe2x80x9d represents any integer including zero.
In the aromatic dihydroxy comonomer compound (IV), when more than one Y1 substituent is present, they may be the same or different. The same holds true for the R1 substituent. When s is zero and u is not zero, the aromatic rings are directly joined with no intervening alkylidene or other bridge. The positions of the hydroxyl groups and Y1 on the aromatic nuclear residues A1 can be varied in the ortho, meta, or para positions and the groupings can be in vicinal, asymmetrical or symmetrical relationship, wherein two or more ring carbon atoms of the hydrocarbon residue are substituted with Y1 and hydroxyl groups. In some particular embodiments, the parameters xe2x80x9ctxe2x80x9d, xe2x80x9csxe2x80x9d, and xe2x80x9cuxe2x80x9d are each one; both G1 radicals are unsubstituted phenylene radicals; and E is an alkylidene group such as isopropylidene. In particular embodiments, both A1 radicals are p-phenylene, although both may be o- or m-phenylene or one o- or m-phenylene and the other p-phenylene.
Some illustrative, non-limiting examples of suitable aromatic dihydroxy comonomer compounds include the dihydroxy-substituted aromatic hydrocarbons disclosed by name or formula (generic or specific) in U.S. Pat. No. 4,217,438. Some particular examples include 4,4xe2x80x2-(3,3,5-trimethylcyclohexylidene)diphenol; 4,4xe2x80x2-bis(3,5-dimethyl)diphenol, 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane; 4,4-bis(4-hydroxyphenyl)heptane; 2,4xe2x80x2-dihydroxydiphenylmethane; bis(2-hydroxyphenyl)methane; bis(4-hydroxyphenyl)methane; bis(4-hydroxy-5-nitrophenyl)methane; bis(4-hydroxy-2,6-dimethyl-3-methoxyphenyl)methane; 1,1-bis(4-hydroxyphenyl)ethane; 1,1-bis(4-hydroxy-2-chlorophenyl)ethane; 2,2-bis(4-hydroxyphenyl)propane (commonly known as bisphenol A); 2,2-bis(3-phenyl-4-hydroxyphenyl)propane; 2,2-bis(4-hydroxy-3-methylphenyl)propane; 2,2-bis(4-hydroxy-3-ethylphenyl)propane; 2,2-bis(4-hydroxy-3-isopropylphenyl)propane; 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane; 2,2-bis(3,5,3xe2x80x2,5xe2x80x2-tetrachloro-4,4xe2x80x2-dihydroxyphenyl)propane; bis(4-hydroxyphenyl)cyclohexylmethane; 2,2-bis(4-hydroxyphenyl)-1-phenylpropane; 2,4xe2x80x2-dihydroxyphenyl sulfone; 2,6-dihydroxy naphthalene; hydroquinone; resorcinol; and C1-3 alkyl-substituted resorcinols.
Suitable aromatic dihydroxy comonomer compounds also include those containing indane structural units such as represented below by the formula (V), which compound is 3-(4-hydroxyphenyl)-1,1,3-trimethylindan-5-ol, and by the formula (VI), which compound is 1-(4-hydroxyphenyl)-1,3,3-trimethylindan-5-ol. 
Also included among suitable aromatic dihydroxy compound comonomers are the 2,2,2xe2x80x2,2xe2x80x2-tetrahydro-1,1xe2x80x2-spirodiols having formula (VII): 
wherein each R6 is independently selected from monovalent hydrocarbon radicals halogen radicals, wherein each R7, R8, R9, and R10 is independently C1-6 alkyl, wherein each R11 and R12 is independently H or C1-6 alkyl, and wherein each n is independently selected from positive integers having a value of 0 to 3 inclusive. In a particular embodiment, the 2,2,2xe2x80x2,2xe2x80x2-tetrahydro-1,1xe2x80x2-spiro-diol is 2,2,2xe2x80x2,2xe2x80x2-tetrahydro-3,3,3xe2x80x2,3xe2x80x2-tetramethyl-1,1xe2x80x2-spirobi[1H-indene]-6,6xe2x80x2-diol (sometimes known as xe2x80x9cSBIxe2x80x9d).
In another embodiment, the disclosure describes articles fabricated from polycarbonates produced by a melt transesterification polymerization by using phosgene and the bis(hydroxyaryl)cyclohexanes previously described and shown in formulas (I) and (II).
In another embodiment, articles fabricated from polycarbonate are prepared by a polymerization method selected from the group consisting of melt transesterification polymerization, interfacial polymerization, interfacial conversion bischloroformate, solid state polymerization, and thin film melt polymerization, wherein the bisphenol composition comprises in addition to the bis(hydroxyaryl)cyclohexane of formulas (I) and (II), at least one aromatic dihydroxy compound comonomer of the formula (III):
HOxe2x80x94A2xe2x80x94OH,xe2x80x83xe2x80x83(III)
wherein A2 is selected from substituted or unsubstituted aromatic radicals.
In the interfacial polymerization method, an aromatic bisphenol is reacted with phosgene in a two-phase reaction medium, comprising an organic and a basic aqueous medium. The organic medium generally comprises a water-immiscible, halogen-containing hydrocarbon solvent, and the basic aqueous medium generally comprises an inorganic base dissolved in water. In general, a lower halogenated alkane, such as dichloromethane is used as the organic solvent. Alkali metal hydroxides, selected from the group consisting of lithium hydroxide, sodium hydroxide, and potassium hydroxide are generally used for to prepare the basic aqueous medium. The polycarbonates produced from the reaction are generally isolated from the organic solution by removal of the organic solvent.
In another embodiment, the articles are fabricated from polycarbonates prepared by a polymerization method selected from the group consisting of melt transesterification polymerization, interfacial polymerization, interfacial conversion bischloroformate, solid state polymerization, and thin film melt polymerization, and which uses the bis(hydroxyaryl)cyclohexanes with the formulas (VIII) and (IX): 
The above bisphenols can be readily prepared using procedures described for example in U.S. Pat. No. 5,480,959.
In another embodiment, at least one aromatic dihydroxy compound comonomer of the general formula (III):
HOxe2x80x94A2xe2x80x94OH,xe2x80x83xe2x80x83(III)
wherein A2 is a substituted or unsubstituted, divalent aromatic radical; is optionally included in the bisphenol composition.
In another embodiment, carbonic esters as shown in Formula (X) are employed in the polymerization reaction,
(ZO)2Cxe2x95x90O,xe2x80x83xe2x80x83(X)
wherein each Z is independently an unsubstituted or substituted alkyl radical, or an unsubstituted or substituted aryl radical. Substituents on Z, when present, may include, but are not limited to, one or more of alkyl, halogen, chloro, bromo, fluoro, nitro, alkoxy, alkoxycarbonyl, methoxycarbonyl, ethoxycarbonyl, and cyano. Some particular examples of the carbonic acid diester suitable for use in the present disclosure include diaryl carbonates, dialkyl carbonates and mixed aryl-alkyl carbonates such as diphenyl carbonate, bis(2,4-dichlorophenyl) carbonate, bis(2,4,5-trichlorophenyl)carbonate, bis(2-cyanophenyl)carbonate, bis(o-nitrophenyl)carbonate, bis{(2-methoxycarbonyl)phenyl}carbonate; bis{(2-ethoxycarbonyl)phenyl}carbonate; ditolyl carbonate, m-cresyl carbonate, dinaphthyl carbonate, bis(diphenyl)carbonate, diethyl carbonate, dimethyl carbonate, dibutyl carbonate and dicyclohexyl carbonate, and combinations of two or more thereof. Of these, diphenyl carbonate is often used in particular embodiments. In some embodiments, if two or more of these compounds are utilized, one is diphenyl carbonate.
In the transesterification melt polymerization, the bis(hydroxyaryl)cyclohexanes as shown in Formulas (I) and/or (II), the optional aromatic dihydroxy compound comonomers of Formula (III), and carbonic acid diesters of the Formula (X) are condensed in the presence of a suitable catalyst. Melt polymerization is accomplished in a process involving one or more stages. The one stage process comprises manufacturing polycarbonates by melt polycondensation of the above bis(hydroxyaryl)cyclohexanes, optional aromatic dihydroxy compound comonomers, and carbonic acid diesters (in the presence of the catalysts. The reactor employed for carrying out these polymerizations is not particularly critical; in some embodiments, it can be made from either glass or metal. In some embodiments, the reactor walls may be further passivated by treatment with a suitable acidic material. If it is desirable to carry out the polymerization in a glass reactor, soaking it in an aqueous acid medium passivates the walls of the reactor. In various embodiments, acids for this process include water solutions of mineral acids, such as hydrochloric acid, sulfuric acid, nitric acid, and the like, and organic acids, such as acetic acid, methanesulfonic acid, toluenesulfonic acid, and the like.
In various embodiments, reactants for the polymerization reaction can be charged into a reactor either in the solid form or in the molten form. Initial charging of reactants into a reactor and subsequent mixing of these materials under reactive conditions for the polymerization may be conducted in an inert atmosphere such as a nitrogen atmosphere. Mixing of the reaction mixture is accomplished by methods known in the art, such as by stirring. Reactive conditions in the present context generally refer to conditions comprising time, temperature, pressure and other factors which result in polymerization of the reactants.
The polymerization is conducted by subjecting the reaction mixture to a series of temperature-pressure-time protocols. This generally involves gradually raising the reaction temperature in stages while gradually lowering the pressure in stages. Preferably the pressure is varied from about atmospheric pressure at the start of the reaction to a value between about atmospheric pressure and about 0.01 millibar pressure; with between about atmospheric pressure and about 0.05 millibar pressure more preferred; and with between about 300 millibars pressure and about 0.05 millibar pressure even more preferred. The temperature is preferably varied between about the melting temperature of the reaction mixture and about 350xc2x0 C., with between about 180xc2x0 C. and about 230xc2x0 C., more preferred, with between about 230xc2x0 C. and about 270xc2x0 C. even more preferred, and with between about 270xc2x0 C. and about 350xc2x0 C. most preferred. This procedure will generally ensure that the reactants react properly to produce polycarbonates with the desired molecular weight, glass transition temperature and physical properties. The reaction proceeds to build the polycarbonate chain with production of phenol by-product. Efficient removal of the phenol by-product by application of vacuum can produce polycarbonates of high molecular weight. If phenol is not removed efficiently, it may participate in the backward reaction whereby the polycarbonate chain is cleaved by phenol in the presence of the polymerization catalyst, thus leading to polycarbonate of lower molecular weight with inferior mechanical and other physical properties. The progress of the reaction may be monitored by measuring the melt viscosity or the weight average molecular weight of the reaction mixture. After the desired melt viscosity and/or molecular weight is reached, the final polycarbonate product may be isolated from the reactor in a solid or molten form.
The methods of producing the polycarbonates are not limited to what is described hereinabove. Thus, the process can be operated either in a batch, semi-batch or a continuous mode. Reaction apparatus known in the art may be used in conducting this reaction, and in some embodiments, may be a horizontal type, tube type, or column type.
The term xe2x80x9calkylxe2x80x9d as used in the various embodiments of the present disclosure is intended to designate straight chain alkyl, branched alkyl, aralkyl, cycloalkyl, and bicycloalkyl radicals. In various embodiments, straight chain and branched alkyl radicals, unless otherwise specified are those containing from 1 to about 40 carbon atoms, and include as illustrative non-limiting examples methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tertiary-butyl, pentyl, neopentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl and dodecyl. In various embodiments, cycloalkyl radicals represented are those containing from 3 to about 12 ring carbon atoms. Some illustrative non-limiting examples of these cycloalkyl radicals include cyclobutyl, cyclopentyl, cyclohexyl, methylcyclohexyl, and cycloheptyl. In various embodiments, aralkyl radicals are those containing from 7 to about 14 carbon atoms; these include, but are not limited to, benzyl, phenylbutyl, phenylpropyl, and phenylethyl. In various embodiments, aromatic radicals used in the present disclosure are intended to designate monocyclic or polycyclic moieties containing from 6 to 12 ring carbon atoms. These aryl groups may also contain one or more halogen atoms or alkyl groups substituted on the ring carbons. In most embodiments, any substituent present is not in a ring position that would prevent an appropriate aromatic radical, such as in a phenolic aromatic radical, from reacting with an appropriate olefinic group, such as in a monoterpene. Some illustrative non-limiting examples of these aromatic radicals include phenyl, halophenyl, biphenyl, and naphthyl. In another embodiment, aromatic radicals used in the present disclosure are intended to designate aralkyl radicals containing from 7 to 14 carbon atoms.
In the preparation of the polycarbonates for forming the articles, the aromatic dihydroxy compound comonomers described above may be used alone, or as mixtures of two or more different aromatic dihydroxy compound comonomers. In one particular embodiment, suitable aromatic dihydroxy compound comonomers for the preparation of a polycarbonate are 2,2-bis(4-hydroxyphenyl)propane (commonly known as bisphenol A or xe2x80x9cBPAxe2x80x9d), resorcinol, or mixtures thereof.
During the manufacture of the polycarbonates by the melt transesterification method, the amount of the carbonic acid diesters is preferably, in an amount of about 0.95 to about 1.30 moles, with an amount of about 1.05 to about 1.15 moles, per 1 mole of the bisphenol component more preferred.
Catalysts that can be used for the melt transesterification polymerization include all those known to be effective for such polymerization. In various embodiments such catalysts are selected from the group consisting of alkali metal compounds; alkaline earth metal compounds, tetraorganoammonium compounds, and tetraorganophosphonium compounds.
Specific examples of alkali metal compounds or alkaline earth metal compounds include organic acid salts, inorganic acid salts, oxides, hydroxides, hydrides, and alcoholates of alkali metals and alkaline earth metals. In some embodiments, the catalyst is an alkali metal compound of the formula M1X1, wherein M1 is selected from the group consisting of lithium, sodium, and potassium; and X1 is selected from the group consisting of hydroxide and OAr, wherein Ar is a monovalent aromatic radical.
More specifically, examples of alkali metal compounds include, but are not limited to, sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium bicarbonate, potassium bicarbonate, lithium bicarbonate, sodium carbonate, potassium carbonate, lithium carbonate, sodium acetate, potassium acetate, lithium acetate, lithium stearate, sodium stearate, potassium stearate, lithium hydroxyborate, sodium hydroxyborate, sodium phenoxyborate, sodium benzoate, potassium benzoate, lithium benzoate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, dilithium hydrogen phosphate, disodium salts, dipotassium salts, and dilithium salts of bisphenol A, and sodium salts, potassium salts, and lithium salts of phenol, etc.
Furthermore, specific examples of alkaline earth metal compounds include, but are not limited to, calcium hydroxide, barium hydroxide, magnesium hydroxide, strontium hydroxide, calcium bicarbonate, barium bicarbonate, magnesium bicarbonate, strontium bicarbonate, calcium carbonate, barium carbonate, magnesium carbonate, strontium carbonate, calcium acetate, barium acetate, magnesium acetate, strontium acetate, and strontium stearate, etc.
In other embodiments, the catalyst is a tetraorganoammonium compound of the formula R4NY2, wherein R is a C1-C4 alkyl group, and Y2 is hydroxide, acetate, or OAr, wherein Ar is a monovalent aromatic radical. In still other embodiments, the catalyst is a tetraorganophosphonium compound of the formula R4PY2, wherein R is a C1-C4 alkyl group, and Y2 is hydroxide, acetate, or OAr, wherein Ar is a monovalent aromatic radical.
Specific examples of tetraorganoammonium compounds and tetraorganophosphonium compounds include, but are not limited to tetramethylammonium hydroxide, tetrabutylammonium hydroxide, tetraethylphosphonium hydroxide, tetrabutylphosphonium acetate, tetrabutylphosphonium hydroxide, etc. Any of the catalysts disclosed above may be used as combinations of 2 or more substances. The catalyst may be added in a variety of forms. The catalyst may be added as a solid, for example a powder, or it may be dissolved in a solvent, for example water or alcohol.
The total catalyst composition is preferably about 1xc3x9710xe2x88x927 to about 2xc3x9710xe2x88x923 moles for each mole of the combination of the bisphenol composition and optional comonomer, and with about 1xc3x9710xe2x88x926 to about 4xc3x9710xe2x88x924 moles more preferred.
Polycarbonates prepared by the transesterification melt polymerization method preferably have a weight average molecular weight of at least about 10,000, a glass transition temperature of at least about 100xc2x0 C., and a dimensional stability as measured by percentage elongation of less than about 0.025% relative to its initial length following exposure to nitrogen with a relative humidity of about 100%, at a temperature of about 23xc2x0 C., and for a duration of about 3 hours.
When the transesterification melt polymerization is carried out in the same manner as described above, but without using aromatic dihydroxy compounds as comonomers, the resulting polycarbonate products have, in one embodiment, a weight average molecular weight of at least about 10,000, a glass transition temperature of at least about 150xc2x0 C., and a dimensional stability of less than about 0.025% relative to its initial length following exposure to nitrogen with a relative humidity of about 100%, at a temperature of about 23xc2x0 C., and for a duration of about 3 hours.
The polycarbonates prepared using any of the polymerization methods previously described can be cast into films by forming a solution of the polycarbonate in a solvent. Suitable solvents include, but are not limited to, halogenated hydrocarbon solvents, such as dichloromethane and 1,2-dichloroethane.
The dimensional stability of the polycarbonates can be measured by placing a polycarbonate film in a controlled chamber and exposing it to a stream of nitrogen maintained at a pre-determined level of humidity and temperature for a specified length of time. The absorption of moisture by the polycarbonate sample will cause the film to swell or elongate. The film is then de-swelled by driving the absorbed out using de-humidified heated nitrogen, and the process is generally repeated to arrive at the percent elongation. In one aspect of this method, the process described above can be repeated more than once, and in some embodiments, three times to arrive at the percent elongation. A low percent elongation is indicative of an outstanding resistance to moisture absorption, which translates to excellent dimensional stability.
Films cast from polycarbonate produced by the melt transesterification polymerization method, as described above, exhibit outstanding dimensional stability in a humid environment, as evidenced by the very low percent elongation of less than about 0.025% of the original length of the film. These materials exhibit much better dimensional stability compared to films made from the reference material, BPA homopolycarbonate and the comparative materials, the polycarbonate copolymer prepared from the interfacial reaction of a 45:55 mole ratio of the monomers, 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane and 4,4xe2x80x2-(m-phenylenediisopropylidene) diphenol, respectively, with phosgene, and the homopolycarbonate derived from reaction of dimethylbisphenol cyclohexanone (DMBPC) with diphenyl carbonate.
In some embodiments, the polycarbonate copolymers consist essentially of structural units derived from the said bis(hydroxyaryl)cyclohexanes or mixtures thereof in combination with structural units derived from a carbonic acid diester and structural units derived from at least one aromatic dihydroxy compound comonomer. In a particular embodiment, the polycarbonate copolymers consist essentially of structural units derived from the said bis(hydroxyaryl)cyclohexanes or mixtures thereof in combination with structural units derived from a carbonic acid diester and structural units derived from at least one of bisphenol A, resorcinol, 4,4xe2x80x2-(1-decylidene)-bisphenol, 2,2-bis(3-sec-butyl-4-hydroxyphenyl)propane or mixtures thereof. In still other embodiments, the polycarbonate copolymers consist of structural units derived from the said bis(hydroxyaryl)cyclohexanes or mixtures thereof in combination with structural units derived from a carbonic acid diester and structural units derived from at least one aromatic dihydroxy compound comonomer. In a particular embodiment, the polycarbonate copolymers consist of structural units derived from the said bis(hydroxyaryl)cyclohexanes or mixtures thereof in combination with structural units derived from a carbonic acid diester and structural units derived from at least one of bisphenol A, resorcinol, 4,4xe2x80x2-(1-decylidene)-bisphenol, 2,2-bis(3-sec-butyl-4-hydroxyphenyl)propane or mixtures thereof. The various structural possibilities that these comonomers can assume have already been described above. In other embodiments, the comonomers include BPA, resorcinol, 4,4xe2x80x2-(1-decylidene)-bisphenol (also referred to as xe2x80x9cbispdedxe2x80x9d), and 2,2-bis(3-sec-butyl-4-hydroxyphenyl)propane (also referred to as xe2x80x9cs-BPAxe2x80x9d). In particular embodiments, aromatic dihydroxy compounds that can be used as comonomers include BPA and resorcinol.
Articles fabricated from polycarbonates prepared using the bis(hydroxyaryl)cyclohexanes by any of the methods mentioned hereinabove are very useful in automotive lighting applications, such as for use as lenses and bezels for headlamps and fog lamps, and in display device applications, wherein high temperature stability may be critical for optimum long-term performance.
Articles comprising the polycarbonates prepared using the proper proportions of the bis(hydroxyaryl)cyclohexanes and the aromatic dihydroxy compound comonomer are used to make a variety of articles suitable for optical media applications. In various embodiments, the polycarbonates for making articles suitable for optical media applications comprise those in which the bis(hydroxyaryl)cyclohexane is at least one of those described herein, and the aromatic dihydroxy compound comonomer is at least one of BPA, resorcinol, bispded, and s-BPA. Articles that can be made include optical articles and display devices. Optical articles that can be prepared using the polycarbonates comprise a film, an optical data storage medium, a rewritable optical disk, and a substrate for an optical data storage medium. The optical articles can function as the protective, transparent layer that covers the various recording media, such as high-density data storage using digital versatile disc (DVD), high density DVD (HDDVD), digital video recordable (DVR), DVD-recordable (DVDxe2x88x92R or DVD+R), and DVD-rewritable (DVDxe2x88x92RW or DVD+RW) formats.
The polycarbonates prepared using any of the methods mentioned hereinabove are also suitable for use in making display devices. One of the components of a display device is the film that forms part of the display panel. The material requirements for such a film include good processibility, high molecular weight, and a glass transition temperature sufficient to withstand the heat generated during the display. By a proper choice of the reacting monomer, polycarbonates having high molecular weight, high glass transition temperatures, and good processibility can be obtained, thus making them useful to produce such films for the display devices. These films can be cast from solutions of the polycarbonates. Such films possess good processibility, outstanding dimensional stability, and a glass transition temperature sufficient to withstand the heat generated during the display.
Another aspect of the present disclosure is a method for making an article that comprises molding a composition comprising the polycarbonates produced by the melt transesterification polymerization methods described above. The process for molding may be selected from the group consisting of injection molding, thermoforming, blow molding, and the like. In various embodiments, the polycarbonates for the molding composition comprise those in which the bis(hydroxyaryl)cyclohexane is at least one of those described herein.
The following examples are included to provide additional guidance to those skilled in the art in practicing the claimed disclosure. The examples provided are merely representative of the work that contributes to the teaching of the present application. Accordingly, these examples are not intended to limit the disclosure, as defined in the appended claims, in any manner.